The United States and its western allies took forceful action against the Syrian government on April 14 when the United States launched a joint airstrike with British and French forces.

The attack came as retaliation for the Syrian government’s use of chemical weapons in an attack near the capital city of Damascus on April 7. While the Syrian government denies the use of chemical weapons in the attack, reports released on April 14 by the French government claimed there was irrefutable evidence of chemical warfare.

According to the Washington Post, the report was released just hours after the coordinated missile strike which targeted labs with the capability of producing chemical weapons.

Though Defense Secretary Jim Mattis said on Friday that there were no plans for additional attacks unless more chemical attacks occur, President Donald Trump tweeted on Friday that the United States would be “prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents.”

While this is not the first time the United States has intervened in the Syrian conflict, the timing of the attack has increased implications for the United States’ dubious relationship with Russia, one of the largest allies of the Syrian government.

This year has already seen US-Russian relations suffer when 60 Russian diplomats were dispelled from the country as a result of the Russian government’s alleged involvement in the poisoning of a Russian double agent on British soil.

According to the New York Times, the Russian government has responded to the attack with threats of retaliation.

“We warned that such actions will not be left without consequences,” Anatoly Antonov, the Russian ambassador to the United States, said in a statement. “All responsibility for them rests with Washington, London and Paris.”